Process of producing olefins



H; F. SAUNDERS.

PROCESS OF PRODUCING OLEFINS.

'APPUCAT|0N FILED MAY 6, I920.

Patented 0m. JILL 1921.,

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NEW JERSEY, nests-Non are THE GLYSYN CORPORATION, OF NEW YO, N. Y., A CORPORATION OF NEW YORK.

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Specification of Letters Patent. Pateimbngdl Unfit. jHL, 1921.

Application filed May 6, 1920. Serial No. 379,318.

To all whom it may concern:

Be it known that I, HAROLD F. SAUNDERS, a citizen of the United States, residing at Bound" Brook, in the county of Somerset and State of New Jersey, have invented certain new and useful Improvements in Processes of Producing Olefins, of which the following is a specification.

My invention relates to a method of producing olefins such a'spropylene and ethylene, in approximately pure state, or definite mixtures of such olefins with each other or with other substances. My invention contemplates using as a raw.material a crude hydrocarbon gas comprlsmg a complex mixture of.

My process may be carried out in a number of ways and consists, generally speaking, in W rectification of crude gas, or of the obtained by its compression, refr1gerliqu'd ation, or both, by a serles of dlstlllatlons 1n which varied pressures or temperatures or both are employed. v

In the form of my process which I deem preferable, the crude gas is compressed at a relatively high pressure so as to liquefy the paraflin oils, higher olefins anda portion of the propylene and ethylene contained in the crude gas, the propylene and ethylene being the olefins which chiefly desire to separate. Theiuncondensed portion of the crude gas contains a proportlon of propylene and ethylene whlch should be added to the liquid portion as far as is possible. I preferably accomplish this enrichment of the liquid by intimately mingling together the gaseous and liquid portions while siibjecting' the mixture to a strong cooling which results in greatly 1n-- creasing the absorptive capacity of the liquid process by passing for the lower olefins;

The liquid thus formed is subsequently treated by pressure and temperature combinations in such a way as to separate out the desired product or products. This is preferably accomplished in a continuous the liquid referred to into a column or chamber which'is maintained at a calculated pressure and m'wluch; a calcracking or distilling eitherratus referred to.

culated temperature gradient is maintained by applying suitable heating or refrigeratmg agencies to the lowerandupper ends of the same. By such means the liquid which 1s progressed into such vessel is constantly separated into a liquid portion at the bottom with a gaseous portion above the same. Under sultable conditions, the desired product such .as propylene may be almost entirely contained in the gaseous portion which is then caused to pass intoa similar vessel in which the application of suitable pressure and a suitable temperature gradient may re-, sult 1n the separation of substantiall'ypure propylene. 1 arious modifications of the above may be employed as will be more fully pointed out hereinafter. t

In order that my invention may be more clearly understood, attention is hereby directed to the accompanying drawing formmg part of this application and illustrating a form ofapparatus by which my improve process may be earned out. The figure shown illustrates diagrammatically a'rectification apparatus.

It should be understood that my novel process is not limited, in the methodof practising the same, to the use of the appa- It also should be understood that various combinations of pressures and temperatures may be used in carrying out the process in accordance with the prin- ,ciples of my lnvention. In order that the same may be more clearly understood, I will describe several means of carrying out the process by way of example, it being understood that the invention is not limited to the specific details of the examples, otherwise than is evidenced by the accompanying claims.

Referring to the drawing, in the production ofpure propylene, crude gas is continuously led from a gas holder A, through the passage 1 to. the compressor '2. The gas is forced by the compressor into chamber 3, 100

where under the high compression employed, such for example as 100 atmospheres, a liquid is separated out. This liquid will consist essentially of parafiin oils, which hold in solu-' tion some of the higher .olefins, such as 105 butylene and amylene, together (I with a certain portion of the propylene and ethylem. The uncondensed portion of the crude gas in chamber 3 consists of a large amount of permanent or inert gases occurring in 110 the original crude gas, such as hydrogen, methane, ethane, nitrogen, eto., holding in suspension a certain quantity of ethylene and propylene.

The propylene and ethylene contained in the gas may belargelycondensed to liquid form by suitable refrigeration and pressure. I have found that the absorption by the liquid fraction formed inchamber 3 of the propylene and ethylene suspended in the gas may very effectively be promoted by intermingling the gas and the liquid while cooling the same.

In carrying out this improved step of the process a pipe 4 may be provided leading from the lower portion of chamber 3 and continuing as a vertical tube 5 terminating at its lower end in a chamber 7. A jacket 6 surrounds the tube 5 and a passage 8 leads from the upper part of chamber 7 'into the lower partof jacket 6, this passage being controlled .by a valve 8. A passage 9 also preferably is used extending from the lower ,portion of chamber 7 to the lower portion of jacket "6, this passage being controlled by valve 9'. I 1

Valves 8 and 9 are expansion valves. The highly condensed gas and liquid in chamber 3 is forced through pipe 4 and its vertical continuation 5 with a, thorough intermingling of the same and a stron cool- I ing efi'ect of the mixture is produce as it passes downwardly through, tube 5. This may be produced by the expansion of the gases in chamber 7 through valve 8 into the jacket 6. from which they may pass through the outlet 10. At the start of the operation the valve 9' may also be opened, allowing some of the liquid in the bottom of chamber 7 to expand through the valve into jacket 6 to aid in bringing the jacket uickly to a low temperature, after which t e valve 9' may be closed and the expansion of the gas through valve 8-alone relied upon to produce the desired chilling of the mixture in tube 5. The temperature of the liquid passing through tube 5 being greatly lowered while its pressure is maintained, its absorptive capacity for propylene and ethylene is materially increased. By chilling the liquid in contact with the inert and uncondensed gas in which the propylene and ethylene are suspended, the greater part of the propylene and ethylene in'the gas are transferred to the liquid.

The gases escaping from outlet 10 consist chiefly of inert or permanent gases, such as methane, ethane, hydrogen, oxygen and nitrogen. When the valve '9 is opened in the preliminary cooling of the apparatus a considerable proportion of propylene and ethylene are carried therewith, and in such a case these gases may be returned from the outlet 10 to the original gas holder. containing'the crude gas before the same is supplied to through tube 11 controlled by valve 12 into column 13. In the example given, this column may be maintained at a pressure of from 15 to 20 atmospheres. A chamber 18 is provided at the lower end of column 13, chamber 18 being surrounded by a jacket or coil or the like 26, while the upper end of column 13 is surrounded by a jacket 29. Heat applied to chamber 18, by passing steam or other heating medium through jacket 26 maintains a temperature in chamber 18 which may be approximately 80 (3., while cold water running through jacket 29 maintains the top of the column at a temperature which may be about 10 C. Consequently there is maintained in column 13 a temperature gradient which, under the pres- -greater proportion of the propylene and ethylene together with such methane, ethane and other inert gases as were originally held in the liquid and carried along therewith.

The liquid which separates out in chamber 18 may be drawn off through valve 21 and carried to any tank or vessel in which its pressure is again lowered to atmospheric. By thus lowering the pressure of this liquid, the propylene and a portion of the higher olefins contained therein are given off in gaseous form and may be returned to the original gas holder to be again introduced into the system, while the paraffin oils remaining as such may be withdrawn and discarded.

.The gas which forms in column 13 above the liquid, and containing a high percentage of propylene together with ethylene and inert ases, is passedthrough passage 16 1 and va ve 16' into column 14, which is simiferent from those in column 13 and may vary from approximately 0 C. at chamber 19, at the bottom of the column, to minus 70 C. at the top of the column. Other combinations of temperature and pressure may, of course, be used to give the same results, depending on the vapor tension of the propylene under the pressure used. In the example given, approximately ure propylene separates in liquid form in c amber 19 and which may be produced by passing the gasthrough a compressor 36 in its passage from column 13 to column 35. A temperature gradient is employed in column 35 such as would be sufiiclent at "the pressure employed to separate the ethylene as a liquid from the 7 bottom. A temperature of 10 C. at the bottom and minus 65 C. at the top are suitable.

To give another example, pure propylene may alsobe obtained in a somewhat different manner, upon introducing the liquid from chamber 7 through valve 12 into column 13, by maintaining a higher pressure in column 13 than in the example first cited. A pressure of -35 atmospheres, for example, would be suitable together with the same temperature gradient as in the example first cited, namely, one produced by a tempera-' ture of approximately 80 C. at the bottom and of about 10 C. at the top. In such a "case a larger proportionof the propylene will remain in chamber 18 in solution in the liquid than in the first example.

If now this liquid in chamber 18 is drawn off from the bottom through pipe connection 18 and valve 17 into column 15, pure propylene may be separated out as a gas in the latter. Column 15 may be entirely similar to the other columns referred to, such as 13 and 14, being provided with a chamber 20 at the bottom for liquids, surrounded by a heating jacket 28, the upper end of the col- .umn being provided with a cooling jacket 31. The pressure to be maintained in column 15 may be the same or higher than that maintained in column 13 in this example, and a temperature gradient maintained by heating the bottom of the column constantl to a. temperature of about 80 (3., and coo ing the top of the column to about 0 C. Tn thi's'case a quite complete separation occurs and,.'pu17e propylene is obtained as gas at This column is maintained at a let valve 34: at the top of the column. The other constituents of the material separate out as a liquid in chamber 20, and may be drawn off through valve 23 and discarded.

A compressor indicated at 37 may be interposed in the path of the liquid passing through connection 18 to column 15, to increase the pressure of the liquid where necessary, and bypass 38 provided with a valve 39 extending around the compressor. Similarly. a compressor 40 may be interposed in the path of gases passing through connection 16 from the upper end of column 13 to column 14:, for use whenever a higher pressure is required in column 14,

and bypam connection 41 being provided around the compressor.

It should be understood that my invention is not limited to the details of the various examples which have been given, the latter. being cited merely as illustrations of the improved process. that the invention is as broad as is indicated by the accompanying claim. In the claim,

the expression definite olefins of low boiling point should be understood as including ethylene, propylene, and definite mixtures thereof.

What I claim is:-

][t should be understood The process of producing propylene, comprising, subjecting a liquid containing paraflins with higher olefins and propylene and inert gases held in solution therein to a pressure of from 15 to 20 at ospheres in a vessel the lower end of which is maintained at" a temperature of about 80 C. while the upper end is maintainedat a temperatureof about 10 C}, passing the gas which separates from the liquid into another vessel which is maintained at the same pressure as the first vessel and at a temperature varying from about 0 C. atthe bottom to minus 70 C. at the top, and drawing. ofi' propylene in liquid form from the bottom of said second vessel. 0

This specification signed and witnessed this 4th day of May, 1920.

HAROLD r. SAUNDERS. 

